1. Field of the Invention
The present invention relates to a focus adjustment device, having an image sensor for generating image signals by forming an image from light flux received through a photographing lens, for carrying out focus adjustment based on the generated image signals, and a control method for a focus adjustment device.
2. Description of the Related Art
It is well known to generate an image signal by photoelectrically converting a subject image based on light flux that has passed through a photographing lens, and carrying out focus adjustment for the photographing lens based on a contrast state of the generated image signal. Detection of a contrast state is generally carried out based on image signals of an AF area that has been set within a shooting screen. In this case, the background of a subject is included within the set AF area, and in a state where the subject and the background image are mixed, AF precision is lowered.
There has therefore been proposed a focus detection device that prevents a background mixing within an AF area and improves AF precision, by carrying out a focus adjustment operation using a smaller AF area included within a normal AF area (refer to Japanese patent laid-open No. 2007-178480).